Adjustable air shield for skewed godet rolls

ABSTRACT

The present invention relates to an adjustable air shield for skewed godet rolls. The air shield can be any blocking type plate with or without perforations. Furthermore, these air shields may be placed in close proximity to the pair of skewed, relax rolls in the relax zone of a fiber producing process. The plates are positioned on the inside of the threadline so that the airflow is substantially reduced around the threadline on the skewed rolls. The preferred embodiment of the present invention is one or more skewed godet rolls in the relax area of the fiber production process with air shields positioned on the inside of the fiber string up (threadline) between the pair of skewed rolls, such that the gap between any roll and any air shield is uniform and constant.

BACKGROUND OF THE INVENTION

(1) Field of the Invention

The present invention relates to an adjustable air shield for skewedgodet rolls in a relax zone during yarn production. Both the adjustableair shield and the adjustable skewed godet rolls are incorporated into arelax zone in the production of yarn to increase the stability of theyarn on the relax rolls, especially at process speeds greater than about4,000 meters per minute. The skew is changed to accommodate processesthat have different deniers (width of filament band on the rolls) and adifferent number of wraps on the rolls. Typical processes that haveapparatus for relaxing the yarn during production are spin-drawing,draw-twisting, draw-winding, and draw-bulking processes. There is thus aneed for a design of adjustable air shields to accommodate changes inroll skew.

(2) Prior Art

The following patents relate to employing an air shield during yarnproduction. Generally these patents teach employing an air shield near apair of godet roll. None of these patents teaches employing adjustableair shields.

Japanese Patent 58-26767 to Ishihara Masatoshi, et al. assigned to TorayIndustries, Inc., describes air shield plates used to prevent yarnvibration thereby enhancing the quality of the wound yarn in high speedwinding applications. This patent employs restricting guides as well asthe air shield plates in FIG. 2 of JP 58-26767.

Japanese Patent 62-116477 to Ohata Takahiro, et al. assigned to TeijinSeiki Company, Ltd., discloses an air shield plate positioned between apair of godet rolls to prevent the occurrence of vibration of the yarn.

Korean Patent Applications 94-4689 and 94-4690 by Baek, et al. andassigned to Cheil Synthetics, Inc., both relate to employing multi-holeair shield plates near the first godet roll to be used at high speedsabove 6,000 meters per minute to prevent air flow thereby reducing fiberbreakage and ensure high productivity of the process.

Japanese Patent 2761789 to Takashi Inoue, and assigned to Teijin Seiki,Co., Ltd., describes an air shield type device. Specifically, two godetrolls are employed where yarn moves excessively on the roll surfaces.Each godet pair consists of a driven roll and a separator roll. The airshield is a single plate mounted between the rolls with one edge inclose proximity to the driven godet roll surface. The plate isperforated with multiple holes which break up the deflected air streamthat bounces off the plate and reduces the incidence of roll wrap.

Published PCT application PCT US02/00153 filed Jan. 3, 2002 discloses atleast a pair of godet rolls with at least one air shield. There is noteaching of adjustability of the air shields with respect to the skewedrolls. This patent application has a common inventor and is commonlyassigned.

The fixed shields, relative to the godet rolls, in the prior art devicesdo not allow for the skew of the rolls to be changed (or adjusted)without changing the geometry and thus the efficiency of the airshields. The skew is changed to accommodate processes that havedifferent deniers (width of filament band on the rolls) and a differentnumber of wraps on the rolls. There is thus a need for a design ofadjustable air shields to accommodate changes in roll skew.

SUMMARY OF THE INVENTION

The present invention relates to an adjustable air shield for skewedgodet rolls. The air shield can be any blocking type plate with orwithout perforations. Furthermore, these air shields may be placed inclose proximity to the pair of adjustable skewed, relax rolls in therelax zone of a fiber producing process. The plates are positioned onthe inside of the threadline so that the airflow is substantiallyreduced around the threadline on the skewed rolls. The preferredembodiment of the present invention is one or more skewed godet rolls inthe relax area of the fiber production process with air shieldspositioned on the inside of the fiber string up (threadline) between thepair of skewed rolls, such that the gap between any roll and any airshield is uniform and constant.

In the broadest sense, the present invention comprises, for use in arelaxation zone of a fiber production process, an adjustable air shieldand a pair of skewed godet rolls.

Likewise, the present invention relates to a process for producingfibers in a relax zone having a pair of skewed godet rolls, comprisingthe step of introducing an adjustable air shield adjacent at least oneof the skewed rolls (relax rolls) in the fiber relaxation zone. Thuswhen the skew of the rolls is reset to accommodate different yarns, theair shield is adjusted such that the gap between any roll and any airshield is uniform and constant.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings are to aid one skilled in the art in understanding thepresent invention and its related concepts as well as the scope of theinvention. However, the drawings are in no way meant to limit the scopeof the invention or impose any limitation on the invention beyond thatset forth in the claims.

FIG. 1 shows a schematic of a pair of adjustable air shields and a pairof skewed godet rolls, with the air shield positioned inside thethreadline between the two skewed rolls.

FIG. 2 shows a second schematic of two pairs of air shields and a pairof skewed godet rolls, where all air shields are inside the threadline.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is directed to adjustable air shields and skewedgodet rolls in a relax zone of a yarn production process. By godetrolls, the inventors are referring to any pair of rolls that has athreadline wound around them. Sometimes the industry refers to a godetroll and a separator roll, or one or more relax rolls. All of thesevarious references are included under the phrase “godet rolls”. Currentprocesses such as a spin draw process, draw twisting process,draw-winding process, or draw bulking process include a relax zone andthus the process and apparatus of the present invention can be employedin such a relax zone.

Any melt-spun polymer employed with any of the above processes such aspolyesters, polyamides (nylons), polyolefins, polyketones,polyetherketones, polyphenylene sulfide, and polyarylates can beemployed with the present invention. Typical polyesters are polyethyleneterephthalate, polybutylene terephthalate, polytrimethyleneterephthalate, polyethylene naphthalate, or a mixture of any of these,or copolymers of any of these polyesters with up to about 15% by weightof other comonomers, such as isophthalic acid. Typical nylons are nylon6 and nylon 66. Typical polyolefins are polyethylene, polypropylene,polybutylene, or a mixture of these. Combinations of any of thesepolymers, or any one of these polymers with other polymers likepolyethylene or polypropylene, in the form of a bicomponent or heterofilfiber are also within the scope of the present invention.

As the relax level increases, yarn tension in the relax zone decreases,and this causes the yarn to become unstable, especially on skewed godetrolls in or downstream of the relax zone. As process speeds increase,instability becomes worse at a constant relax ratio, due to the increasein centrifugal force on the yarns on the skewed relax rolls. Thus asprocess speeds are increased, relax level must be decreased to maintainstability. Unstable yarn is defined as yarn moving, or swaying acrossthe roll surface of the skewed godet rolls due to low tension. Highlyunstable yarn can lead to a reduction in mechanical quality, and insevere cases, to breakouts (yarn breakage). The skew for godet rolls isdifferent for different process conditions, such as denier of the yarn,process speed, amount of relax, and type of synthetic yarn, for example.Therefore, the skew of godet rolls may be varied to accommodate runningdifferent products on the same equipment.

When the process or apparatus of the present invention is used in any ofthe yarn production processes having a relax zone, a higher level ofrelax and a resulting lower hot air shrinkage can be achieved ascompared to conventional processes and apparatus having no air shields.By using the present invention at higher processing speeds one canachieve the same level of relax under high speed conditions versus moreconventional low speed conditions, or one could maintain the processspeed but increase the level of relax such that the hot air shrinkage isgreatly improved (reduced), or both can be done simultaneously.

FIG. 1 schematically illustrates the present invention comprising theadjustable air shields and skewed rolls. Referring to FIG. 1, reference10 generally indicates the apparatus of the present invention positionedin a relax zone of a fiber production process. The relax zone has a pairof spaced apart, skewed, godet rolls 12, 14. Generally these rolls areadjustable such that the skew angle can be varied. The details of thisadjustability are not essential to understanding the present inventionsince there are several solutions to vary the angle of the rolls. Theserolls may be the same size, different sizes, and constructed of the sameor different materials. A fiber threadline 16 is wrapped multiple timesaround the rolls 12, 14. Each roll has an air shield 18 mounted adjacentthe rolls 12, 14 and are spaced approximately 1 to 5 mm (preferably 1 to2 mm) from the rolls. The shields 18 may be perforated or solid as knownin the art. The air shield 18 is supported by a support frame or bar 20that may be secured to the supporting framework 22. Preferably theconnection between the frame or bar 20 and the framework 22 includes aswivel joint 24 so that the bar 20 can be positioned at any angle to theframework, and preferably parallel to its related skewed roll. It isalso preferred that the framework 22 includes an elongated slot 26 thatthe swivel joint is positioned within, so that the air shield may befurther adjusted relative to the roll it is associated with. Dependingupon the string-up conditions and the production parameters, the skew ofthe rolls 12, 14 to one another may be changed. With the preferred useof a swivel joint 24 and an elongated slot 26, maximum flexibility canbe obtained by allowing the adjustment of the air shields to the rolls.

The air shield is positioned inside of the threadline 16 so that airflowis blocked from blowing across the threadline and creating movement onthe skewed rolls 12, 14. The air shield 18 comprises at least one plate(thin and flat substantially two dimensional) and preferably a pair ofplates are employed, one per roll as shown. The plates may be made fromany material capable of being perforated or being solid such as metal,like aluminum or copper for example (virtually any metal will performequally well); plastic capable of withstanding the heat generated duringthe relaxation stage of the fiber making process, like polycarbonate,polyester, polyamide, all of which are well known in the art; wood,rubber; or a combination of these. The air shield may be any shape, notnecessarily rectangular or square, because the rolls 12, 14 are skewed.Preferably the spaced apart plates 18 are positioned between the skewedrolls 12, 14 and within each tangent line connecting the outer surfaceof each roll, and thus within the threadline 16. When one air shield isused per roll as shown in FIG. 1, the air shield 18 is positioned on thethreadline discharge side of the roll. The air shields block the flow ofair generated by the rotation of the skewed rolls 12, 14 and any airflowcaused by fans or blowers in a production facility, for example. Byvirtue of the fact that the air shield 18 is positioned approximately 1to 5 mm (preferably 1 to 2 mm.) from rolls 12, 14 and are also about thesame distance from the threadline 16, a quiescent zone adjacent each airshield 18 is created thus significantly reducing any disruption of themovement of the threadline on rolls 12, 14 induced by air currents.

In operation of the FIG. 1 device, a threadline 16 coming from the drawstage (not shown), for example, is wrapped multiple times about the pairof skewed rolls 12, 14. The function of the rolls 12, 14 is not a partof the present invention and depends upon the type of process in whichthe relax zone is present (the relax zone includes the rolls 12, 14).Therefore the rolls 12, 14 could be in a spin-drawing process, or in adraw-twisting process, or in a draw-winding process, or a pair of rollsin a draw bulking process. The threadline is wrapped multiple timesabout the rolls 12, 14 and exits the rolls to further processing orwinding. Because the air shields 18 are positioned inside of thethreadline 16, created by the multiple wraps of the yarn or fiber 16,the air shields 18 do not interfere with string-up, for example.

FIG. 2 illustrates a modification of FIG. 1 of the present invention inwhich two pairs of air shields are employed per skewed roll. Allreferences to numerals in FIG. 1 apply equally to FIG. 2. To furtherreduce air currents around the skewed rolls 12, 14, each roll has a pairof air shields 18 are positioned inside the threadline and are betweenthe rolls 12, 14 so that the air is blocked from the treadline 16 uponboth entering a roll and leaving a roll. Thus even less instability ofthe treadline is present in the FIG. 2 device as compared to the FIG. 1device.

The operation of the FIG. 2 device is substantially similar to that ofthe FIG. 1 device.

Those skilled in the art may recognize that a larger diameter roll likeroll 12 would create more air currents at its larger surface than asmaller diameter roll like 14. Thus its within the present invention tohave 3 air shields where the larger roll has a pair of shields while thesmaller roll has only a single air shield. Likewise, it is within theskill of the artisan to provide only one air shield at the exit side ofthe threadline adjacent the larger roll, and no air shield on thesmaller roll.

Thus it is apparent that there has been provided in accordance with theinvention a process and an apparatus that fully satisfies the objects,aims, and advantages set forth above. While the invention has beendescribed in conjunction with specific embodiments thereof, it isevident that many alternatives, modifications and variations will beapparent to those skilled in the art in light of the foregoingdescription. Accordingly, it is intended to embrace all suchalternatives, modifications and variations as fall within the spirit andthe broad scope of the claims.

1. In a yarn making process having at least one pair of skewed rolls,comprising: providing an adjustable air shield adjacent at least oneskewed roll to reduce air buffeting the yarn on the skewed rolls.
 2. Inthe yarn process of claim 1, said adjustable air shield is positionedbetween said pair of skewed rolls and one edge of said air shield isfrom about 1 to about 3 cm from said at least one skewed roll.
 3. In theyarn process of claim 1, wherein said adjustable air shield includes aswivel joint.
 4. In the yarn making process of claim 1, wherein saidyarn is polyester and said polyester yarn is wrapped about each of saidskewed rolls multiple times.
 5. In the yarn making process of claim 1,said process comprising: spin drawing, draw-twisting, draw-winding, ordraw-bulking process.
 6. In the yarn making process of claim 1, whereinsaid adjustable air shield comprises a pair of plates.
 7. In the yarnmaking process of claim 6, wherein said plates are positioned betweensaid skewed rolls.
 8. Apparatus for use in a yarn making process,comprising: a pair of spaced apart skewed rolls, and at least oneadjustable air shield positioned between said skewed rolls.
 9. Theapparatus of claim 8, wherein said adjustable air shield comprises apair of plates positioned between said skewed rolls.
 10. The apparatusof claim 9, wherein said plates are positioned from about 1 to 5 mm.from said skewed rolls.
 11. The apparatus of claim 9, wherein saidplates are positioned from about 1 to 5 mm. from one of said skewedrolls.
 12. The apparatus of claim 11, wherein a third adjustable airshield plate is positioned adjacent the other skewed roll.
 13. Theapparatus of claim 9, wherein said plates are spaced apart, positionedbetween said rolls and are within each tangent line connecting the outersurface of each roll.
 14. The apparatus of claim 9, wherein each of saidplates is securely fastened to a bar.
 15. The apparatus of claim 14,wherein said bar includes a swivel joint positioned on one end thereof.16. The apparatus of claim 14, wherein one end of said bar is adjustablysecured to structural framework.
 17. The apparatus of claim 16, whereinsaid bar includes a swivel joint positioned on said one end thereof. 18.The apparatus of claim 17, wherein said structural framework includes anelongated slot in which said swivel joint is positioned.
 19. Apparatusfor use in a yarn making process, comprising: a pair of spaced apartskewed rolls, and two pair of adjustable air shields positioned betweensaid skewed rolls.
 20. The apparatus of claim 19, wherein one pair ofsaid adjustable air shields is positioned adjacent each of said skewedrolls.
 21. The apparatus of claim 20, wherein each of said plates issecurely fastened to a bar.
 22. The apparatus of claim 21, wherein oneend of each of said bars is adjustably secured to structural framework.